Grooving knife assembly

ABSTRACT

A blade holder with parallel horizontally spaced feet for support on a board surface, with inverted channel-shaped bridge portion between the feet and a handle atop the bridge portion. Two pairs of knife blades, each pair removably secured to the bridge portion adjacent one of the feet, and including two generally triangular blades substantially identical except for a horizontally turned tip portion of one blade intercepting the path of the other, the blades of each pair being closely horizontally spaced the width of the desired groove to be cut in the board.

United States Patent [72] lnventor John E. ONeal Indianapolis, Ind. [2]] Appl. No. 744.013 [22] Filed July 11,1968 [4S] Patented Aug. 3, 1971 [73] Assignee John J. Cotton Indianapolis, Ind. a part interest [54] GROOVING KNIFE ASSEMBLY 3 Claims, 4 Drawing Figs.

[52] US. Cl 30/279, 30/280, 83/5 [5]] Int. Cl B26b 3/04 [50] Field of Search 30/280, 287, 293, 294, 304, 279; 172/378, 379; 83/5 [56] References Cited UNITED STATES PATENTS 442,878 12/1890 Geiger 83/5 964,453 7/1910 Robarge 30/280 X 1,854,481 4/1932 Mudd 83/5 X 1,955,395 4/1934 Tueth.... 30/280 X 2,097,811 11/1937 Foley 30/280 X 2,230,042 1/1941 Mertens 30/294 X Primary Examiner-Robert C. Riordon Assistant Examiner-J. C. Peters ArrorneyWoodard, Weikart, Emhardt & Naughton PATENIEn ms 3mm v 596, 356

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BY 240 W C MMW 45 rneyj GROOVING KNIFE ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to knives, and more particularly to knife assembly well adapted to providing grooves or channels in boardlike material.

2. Description of the Prior Art Some prior art patents dealing with knives or tools for grooving or slitting are as follows: U.S.Pat. Nos. 2,013,780 to Holzheirner, Sept. 10, I935; 2,558,111 to Tiemann, June 26, 1951; 2,721,384 to Bell, Oct. 25, 1955; 2,952,025 to Johnson, Sept. 13, I960. The Johnson device is intended for sheet materials including plaster board, rock lath and the like. The Holzheimer device is intended for carving in furniture and other articles.

In heating and air-conditioning installations, increasing attention is being given to ductwork made of insulation board combining a basic board of glass fibers with a backing including a plastic sheet with fabric strengthener and reflective foil. It is desirable to be able to work with such ductwork conveniently and effectively. This includes formation of units having circular cross section.

Because of the fact that the board is normally manufactured and furnished in a flat configuration, the formation of units of circular cross section requires some grooving of the board. The present invention is directed toward a knife assembly well adapted to producing the type of grooving most effective in working with such board to provide the desired shapes.

A knife assembly is known for cutting a V-shaped groove and has some similarity to the Holzheimer patent in that respect. However, I have found that the V-shaped groove is not particularly satisfactory.

SUMMARY OF THE INVENTION Described briefly, in a typical embodiment of the present invention a knife holder with a handle thereon, has lower surface means adapted to reception and bearing on the surface of a board to be grooved. Tow pairs of horizontally spaced blades are provided, each pair being spaced a considerable horizontal distance from the other pair to provide the desired spacing between grooves to be cut in the board. Each pair of blades has a horizontally turned portion to cut the bottom of the groove, while the vertical portions cut the sidewalls of the groove. Front and rear edges of the blades are sharpened so a cut can be made by moving the tool in either a forward or reverse direction through the material.

BRIEF DESCRIPTION OF THE DRAWINGS The full nature of the invention will be understood from the accompanying drawings and the following description and claims.

FIG. 1 is an elevational view of the tool applied to a board, the latter being shown in section.

FIG. 2 is a bottom plan view of the knife assembly.

FIG. 3 is a side elevational view thereof.

FIG. 4 is an end view of a round duct section formed by bending the insulating board in a circle after grooves are cut therein by a knife assembly according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, as shown in FIGS. 1 and 3 a handle 11 is mounted atop the horizontal bridge por tion 12 of a knife holder, the bridge portion having downwardly turned sidewalls 13 which are outwardly turned at their lower margins to provide horizontally extending feet 14, the lower surfaces 16 of these feet being rested upon the top face 17 of the insulation board 18 which is to be grooved. This board has a backing 19 typically of a combination cloth fabric, plastic and reflecting foil. Such board is comparatively rigid and, unless appropriate grooves are provided therein, it cannot be formed in the manner illustrated in FIG. 4 without damage. As shown in FIG. 4, a plurality of grooves 21 equally spaced from each other meet the inner wall 17 and the backing 19 is lapped at 22. The grooves are actually closed up in FIG. 4 and it is this feature that accommodates the bending of the board in the circle.

Referring further to FIG. 1 in particular two grooves are shown at 21. Referring to one of these grooves, it is formed by a pair of knife blades 23 and 24 which are horizontally spaced the desired width of the groove. These blades can be identical except for the fact that the lower marginal portion of blade 23 is turned inwardly at 26 and crosses the path of blade 24. Both blades are secured to the bridge portion 13 by a screw 27, a nut 28 providing the desired horizontal spacing between the blades and the nut 29 securing blade 24 in place.

As shown in FIG. 3, the leading edge 31 of blade 23 is inclined downwardly and to the rear, and the trailing edge 32 is inclined upwardly and to the rear. The trailing edge 33 of blade 24 is inclined upwardly and to the rear, and the leading edge 34 of this blade is inclined downwardly and to the rear. The leading and trailing edges 34 and 33, respectively for blade 24 lie in a plane perpendicular to the plane of the lower faces 16 of the feet of the blade holder. Similarly the leading and trailing edges 31 and 32, respectively, of blade 23 lie in a plane perpendicular to the plane of the bearing faces 16 of the blade holder 8. These planes are horizontally spaced the width desired for the groove in the board and are intercepted by the transverse blade portion 26 which lies in a plane perpendicular to the planes of the leading and trailing edges, and parallel to the plane of the faces 16. Notice in FIG. 2 that the leading and trailing edges 36 and 37, respectively of the horizontal blade portion 26 are also inclined. At this point it might be recognized that blades 2.3 and 24 can b identical except for the inwardly turned portion of blade 23. In other words, blade 23 would be identical to blade 24, were it not for the fact the tip portion of blade 23 is inwardly turned at 26. By appropriate selection of apertures in these two blades, they can be mounted either to the left-hand wall or right-hand wall 0 the bridge portion of the holder. Likewise the proper offset, best shown in FIGS. 3 and 2, between the leading edges of the blades can be provided to accommodate the location of trailing edge 37 of blade portion 26 immediately adjacent leading edge 34 of blade 24 at the point 38.

Reference to the various edges as leading and trailing edges imply that the motion of the knife assembly for cutting action is in the direction of arrow 39 (FIGS. 2 and 3). However the cutting action can be just as effective by moving the assembly in the opposite direction The upwardly inclined ends of the feet 14 are helpful in moving the tool in either direction while it is supported on the board. The area of blade portion 26 facilitates lifting the cut piece out of the board once the pass of the blades through the board has been accomplished.

From the foregoing description, it will be recognized that the spacing between the channels cut in the board will be determined by the width of the bridge portion 12. If desired to provide a closer spacing between channels, it is only necessary to move the assembly laterally half the total spacing between two of the channels cut at a time, and make another pass through the board. This will double the number of grooves which would be provided otherwise.

The width of the grooves can be selected as required, dependingon the radium of the end product to be produced, whether it be a circular duct, or part of an elbow in rectangular duct, or whatever it is. This can be accomplished easily by employing washers or nuts of varying thicknesses in the place of the nut 28, the thickness being determined by the desired groove width. The blade mounting arrangement also facilitates removal for sharpening or replacement.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention reference being made to the appended claims.

The invention I claim is:

l A grooving knife assembly comprising:

a holder having feet thereon with lower faces adapted to reception and bearing on the surface of a board to be grooved;

blade means secured to said holder and including a first blade projecting below a first plane of said faces and hav ing front and rear inclined edges lying in a second plane substantially perpendicular to said first plane,

said blade means further including a second blade in parallel horizontally spaced relation to said first blade and having a lower portion turned transversely and crossing said second plane of said first blade for butting a channel in said board;

said first and second blades having identical inclines on the edges thereof, an edge of said first blade being horizontally offset with respect to a corresponding edge of said second blade.

2. The assembly of claim 1 wherein:

a point on the trailing edge of said transversely turned portion of said first blade is disposed immediately adjacent a point on the leading edge of said second blade.

3. The assembly of claim 2 wherein:

said blades are secured to said holder by a screw received in an upturned wall of said holder at the edge of one of said feet, with first nut means on said screw providing a spacer between said blades to establish the horizontal spacing between them. 

1. A grooving knife assembly comprising: a holder having feet thereon with lower faces adapted to reception and bearing on the surface of a board to be grooved; blade means secured to said holder and including a first blade projecting below a first plane of said faces and having front and rear inclined edges lying in a second plane substantially perpendicular to said first plane, said blade means further including a second blade in parallel horizontally spaced relation to said first blade and having a lower portion turned transversely and crossing said second plane of said first blade for butting a channel in said board; said first and second blades having identical inclines on the edges thereof, an edge of said first blade being horizontally offset with respect to a corresponding edge of said second blade.
 2. The assembly of claim 1 wherein: a point on the trailing edge of said transversely turned portion of said first blade is disposed immediately adjacent a point on the leading edge of said second blade.
 3. The assembly of claim 2 wherein: said blades are secured to said holder by a screw received in an upturned wall of said holder at the edge of one of said feet, with first nut means on said screw providing a spacer between said blades to establish the horizontal spacing between them. 